The present invention relates to pintle-type valves; more particularly to solenoid-actuated pintle valves for permitting the controlled admission of exhaust gases into the fuel intake manifold of an internal combustion engine; and most particularly to a system including an interrupted pintle and gas arrestor for preventing entrance of corrosive gases and moisture into the valve actuator.
It is well known in the automotive art to provide a variable valve connecting the exhaust manifold with the intake manifold of an internal combustion engine to permit selective and controlled recirculation of a portion of an engine""s exhaust gas into the fuel intake stream. Such recirculation is beneficial for reducing the burn temperature of the fuel mix in the engine to reduce formation of nitrogen and sulfur oxides which are significant components of smog. Such a valve is known in the art as an exhaust gas recirculation (EGR) valve.
Typically, an EGR valve has a valve body enclosing a chamber disposed between a first port in the exhaust manifold and a second port in the intake manifold; a valve seat dividing the chamber between the two ports; a pintle shaft having a valve head fitted to the valve seat and extending from the valve head through a bearing mounted in a third port in a sidewall of the valve body; a spring-retained bearing splash shield; and a solenoid actuator mounted on the exterior of the valve body and having an armature into which the outer end of the valve pintle extends.
A problem inherent to EGR valve applications is that the managed fluid (exhaust gas) is moisture-laden, corrosive, and dirty. If this gas enters the actuator, for example, by leaking along the pintle shaft, then internal corrosion, malfunction, and ultimate failure of the actuator can result. Such failure can lead to emission non-compliance and can incur significant cost to a vehicle manufacturer if a recall is required. Two known solutions to this problem are a sealed, impermeable actuator, or, alternatively, an actuator having working components which are unaffected by exhaust gas. Either of such actuators is currently impractical for cost and performance reasons. Further, a sealed actuator would be even more vulnerable to damage from trapped moisture if a leak should develop in the seal; and a corrosion-resistant actuator would require materials of construction which are less magnetically efficient than the currently used soft iron and powder metals, thus dictating a substantially larger solenoid.
What is needed is a gas arrestor between an EGR valve and actuator that prevents gas and moisture intrusion into the actuator without impairing efficiency, size, and performance of the valve and actuator. Preferably, such an arrestor is simple and inexpensive to fabricate and install.
The present invention is directed to a leakage arresting system comprising a novel gas arrestor for installation on an interrupted pintle shaft in a pintle-type valve, such as an exhaust gas recirculation valve for an internal combustion engine, for preventing leakage of gas and moisture along the pintle shaft into the actuator to prevent corrosion and failure of the actuator. The system comprises two elements: a pintle shaft which is interrupted outside the actuator, and a positive vapor block in the form of a cup-shaped arrestor disposed across the pintle interruption. The invention is applicable to both unbalanced and force-balanced valves.